A nonlinear creep damage model for salt rock
A nonlinear creep damage model for salt rock
复制标题
盐岩非线性蠕变损伤模型
DOI：
10.1177/1056789518792649
复制
发表时间：
2019-05-01
影响因子：
4.2
通讯作者：
Zou, Quanle
中科院分区：
文献类型：
--
作者：
Wu, Fei;Chen, Jie;Zou, Quanle
在蠕变试验中，应力不再是常数，而是在加速蠕变过程中发生的损伤的影响下逐渐增加，这是一个缓慢的加载过程，而不是传统的蠕变。随着时间的推移，随着损伤的积累，实际应力大大增加。实际应力的增加不仅产生加载应变，而且使稳态蠕变速率增大。这种耦合可能解释了盐岩在加速蠕变阶段呈现非线性加速特性的原因。在这项工作中，通过假设加速蠕变阶段是加载和蠕变的耦合过程，克服了目前蠕变概念的约束。此外，我们证明了在这个阶段的总应变等于加载应变和蠕变应变的总和。推导了一个新的非线性蠕变本构方程，并进一步解释了加速蠕变阶段出现的非线性加速特性的机理。对盐岩进行了为期6个月的分级加载试验。在加载的最后阶段出现了加速蠕变的特征。利用该非线性蠕变损伤本构模型对试验数据进行拟合和分析。结果表明，该模型与试验数据拟合良好，能较好地反映加速蠕变的非线性特征，从而支持了该模型的有效性。
In the creep tests, stress is no longer a constant and increases gradually under the influence of damage occurring during accelerating creep, which is a slow-loading process rather than a conventional creep. With the accumulation of the damage over time, the actual stress increases greatly. The increased actual stress not only generates loading strain but also causes the steady creep rate to rise. This coupling possibly explains why salt rock presents nonlinear accelerating characteristics at the accelerating creep stage. In this work, the constraint of the present creep concept was overcome by assuming that the acceleration creep phase is a coupling process of loading and creeping. Furthermore, we demonstrate that the total strain in this phase is equal to the sum of loading strain and creeping strain. A new nonlinear constitutive equation for creep was then derived, and the mechanisms underlying the nonlinear accelerating characteristics emerging at the stage of accelerating creep are further explained. A step-loading experiment on salt rock was performed for a period of six months. The characteristics of accelerating creep appeared in the last step of loading. This new nonlinear creep damage constitutive model was used to fit and analyze the test data. Obtained results show that this model fits well to these test data and also favorably represents the nonlinear characteristics of accelerating creep, thus supporting the model's validity.